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Watching a TV programme about the Himalayas, they mentioned water takes
longer to boil at altitude.
Why is this? I think it must be something to do with pressure, but why and
what is the principal?
Thank you,
Dribbler

"Dribbler" <> wrote:

>Watching a TV programme about the Himalayas, they mentioned water takes
>longer to boil at altitude.
>Why is this? I think it must be something to do with pressure, but why and
>what is the principal?
>Thank you,
>Dribbler
>

Did they say it takes longer to get water to boil, or did they say
that you have to boil things longer at high altitudes?

The reduced air pressure means that water will boil at a lower
temperature at high altitude. And once it reaches the boiling point
it will not get any hotter - just boil faster.

The lower boiling temperature means that things take longer to cook.
So pasta that cooks in 10 minutes at sea level might require 12
minutes or more to cook properly in boiling water at high altitude.


Ron Martell Duncan B.C. Canada
--
Microsoft MVP
On-Line Help Computer Service
http://onlinehelp.bc.ca

"The reason computer chips are so small is computers don't eat much."

Dribbler wrote:

> Watching a TV programme about the Himalayas, they mentioned water takes
> longer to boil at altitude.
> Why is this? I think it must be something to do with pressure, but why and
> what is the principal?
> Thank you,
> Dribbler
>

Homework?
http://www.newton.dep.anl.gov/askasc...0/phy00162.htm

"Dribbler" wrote
> Watching a TV programme about the Himalayas, they mentioned water takes
> longer to boil at altitude.
> Why is this? I think it must be something to do with pressure, but why and
> what is the principal?

This is because the air pressure is lower at high elevations.
Water at sea level boils at 100C and freezes at 0 degrees.
At higher elevations, where atmospheric pressure is lower,
water's boiling temperature is lower, so it takes longer to
boil or cook things.

It boils at a lower temperature at altitude.

Boiling occurs when the water is hot enough to have the
same pressure as the surrounding air, so that it can form bubbles. As water
is heated, its steam pressure rises, until it reaches the pressure of the
surrounding air. At high altitudes, this air pressure is lower than at sea
level, so the water doesn't have to get so hot to get to boiling.

--

Kenny


"Dribbler" <> wrote in message
news:4165afba$0$8474$. ..
> Watching a TV programme about the Himalayas, they mentioned water takes
> longer to boil at altitude.
> Why is this? I think it must be something to do with pressure, but why and
> what is the principal?
> Thank you,
> Dribbler
>
>

"Kenny" <> wrote in message
news:...
> It boils at a lower temperature at altitude.
>
> Boiling occurs when the water is hot enough to have the
> same pressure as the surrounding air, so that it can form bubbles. As
water
> is heated, its steam pressure rises, until it reaches the pressure of the
> surrounding air. At high altitudes, this air pressure is lower than at sea
> level, so the water doesn't have to get so hot to get to boiling.

> Kenny

Thankyou Kenny, you explain it so well!
I appreciate all the replies, I feel rather daft for not knowing and for
not being able to locate the answer myself on Google.
Thanks!
Dribbler

In article <2Gi9d.289831$>, Liz says...
> "Dribbler" wrote
> > Watching a TV programme about the Himalayas, they mentioned water takes
> > longer to boil at altitude.
> > Why is this? I think it must be something to do with pressure, but why and
> > what is the principal?
>
> This is because the air pressure is lower at high elevations.
> Water at sea level boils at 100C and freezes at 0 degrees.
> At higher elevations, where atmospheric pressure is lower,
> water's boiling temperature is lower, so it takes longer to
> boil or cook things.
>
Did you actually read that? The boiling point is lower thus requiring
less heating up but it takes longer?


--
Conor

Opinions personal, facts suspect.

Dribbler wrote:
>
> Watching a TV programme about the Himalayas, they mentioned water takes
> longer to boil at altitude.
> Why is this? I think it must be something to do with pressure, but why and
> what is the principal?

Since a watched pot never boils put a lid on it.

"Dribbler" <> wrote in message
news:4165afba$0$8474$. ..
> Watching a TV programme about the Himalayas, they mentioned water takes
> longer to boil at altitude.
> Why is this? I think it must be something to do with pressure, but why and
> what is the principal?
> Thank you,
> Dribbler
>
>
I saw that too. It's wrong, or at least badly expressed Water will reach
its boiling point quicker at altitude because the boiling point is reduced -
lets say it boils at 95 rather than 100C. Food boiled at 95C will take
longer to cook than at the normal 100C.

Alan

"Conor" <> wrote
> In article <2Gi9d.289831$>, Liz says...
> > "Dribbler" wrote
> > > Watching a TV programme about the Himalayas, they mentioned water takes
> > > longer to boil at altitude.
> > > Why is this? I think it must be something to do with pressure, but why and
> > > what is the principal?
> >
> > This is because the air pressure is lower at high elevations.
> > Water at sea level boils at 100C and freezes at 0 degrees.
> > At higher elevations, where atmospheric pressure is lower,
> > water's boiling temperature is lower, so it takes longer to
> > boil or cook things.
> >
> Did you actually read that? The boiling point is lower thus requiring
> less heating up but it takes longer?

Do you have trouble understanding food takes longer to cook
at a lower temperature?